from what i understand, it was real as in r&d was real, but not much came out of this. in regard to nukes, maybe this programme provided some new fancy sensors. one of the logical responses to things like SDI is to increase number of ICBMs and decoys, which is exactly what soviets did, it doesn't require developing similar ABM system. (nukes are ultimately tools of diplomacy, not really tools of war) of other things, we know that neutral particle beams work. some western weaponeers are toying with idea of high power lasers, but star wars era stuff were chemical lasers and what is used now are fiber lasers, so it's not directly transferable

also Teller was insane and x-ray lasers never worked